Defrosting means for refrigerating systems



Sept. 18, 1956 E. SQRENSEN DEFROSTING MEANS FOR REFRIGERATING SYSTEMS Filed Dec. 13, 1954 IN V EN TOR. L JNAR SORENSEN ATTORNEY if g .room or chamber, A indicated by thedashed line.

United States Patent o DEFROSTING MEANSFOR SYSTEMS Ejnar Sorens en, Hollywood, Calif. Application December 13, 1954, tserialaNo. 474,713 "12 Claims. 61. 52- 3) My invention relates to refrigerating systems and more particularly to defrosting means'forsuch systems. It is an object of my inventionto provide an improved means for'quickly and thoroughly defrosting a refrigerating system by introducing hot refrigerant into the evaporator, draining the resultant liquid into-a tank and thereafterreturning the refrigerantto the evaporator for resumption of operation ofthe refrigerating system.

More specifically it is an object of this invention to provide a defrosting mean such as described in which the hot refrigerant enters the top or outlet-sideof the evaporator, passes through the evaporator tothe bottom and then drains'from the evaporator into a tank connected in the system and controlled in -a :novel manner whereby after the defrosting operation, the refrigeranh as a liquid is returnedto the evaporator withouthaving been passed As arethan heretofore.

It is another object of my inventionto provide an improved defrosting system such as described which may Ibe. employed effectively with-systems having a plurality of evaporatorsas well as in asystem having a single evaporator.

I'willdescribe only one form of refrigerating system .embodyingmy invention, rand-will then'point out the .novel features thereof in claims.

The single figure in the drawing is, a diagrammatic illustration'of a refrigerating system provided with defrosting 1 means embodying my invention.

As. shownin the accompanying drawing, my. invention isembodied in a refrigerating systemof the floodedtype. The. evaporator 1 of thissystem is disposed-in a cooling Air is circulated over the evaporator :bymeans ofthe motor driven blower 2. A water drain 1a is provided for the -.evaporator housing.

A compressor 3 discharges the refrigerant-through a pipe line 4to a condenser 5 from which the refrigerant passes through pipe li-ne'6 into the liquid receiver 7.

.From the receiver-7, a pipe line8 conducts the refrigerant ,to an accumulator '9 from where the refrigerant enters the evaporator through-a pipe line 10 leading into the vcoils of the evaporator. .In the line 8 is a solenoidconnected in a line extending from the upper-part of :the evaporator 1 intothe upper end of the accumulator 9. A valve 14a is provided in the line 14.

'In-accordance'with my invention, a large. closedtank 1216 is disposed to receivefthe rrefrigerantz-frorn' the evaptorato -t mugh admi -l ne 1*7 .s. bjec ;to controlbymeans Patented Sept. 18, 1956 ice the bottom to the top of the tank, and operates'a magnetic switch 27 to control an electric circuit' 29 for thesolenoid valve 28 in the line 8 leading from the liquid-receiver 7. Another electric circuit 29a connects-in series the blower 2 and the solenoid valve 11. These circuits are supplied through a switch box 30 towhich line conductors'31lead from a suitable source. Switch means, not shown, in the box 30 provides for control of the circuit for the blower 2 and solenoid valve '11. V

Leading from the compressor suction line 23 to the tank 16 is pipe line 32 having a shut-off valve 33. A bypass pipe 34 connects the tank 16 with thepipe line 32 and is provided with a pressure regulator 35. A pipe line 36 connects the pressure regulator 35 with a discharge pipe line 37 which latter leads from the suction line'14 into the tank 16. "The line 37 is controlled by a valve 38.

From the liquid line 8 a pipe line '39 leads into the tank'16. Acheck valve 40 in the line'39' prevents liquid from the line -8 from flowing into the tank 16 but permits flow from the tank into the line 8. A manually operable valve41 is provided in the line'39.

It will now be apparent that'this system will operate 'in the known manner to cool the chamber indicated by the dashed line A.

16' under-suction. 'Valve38 is now opened whereby the line 37 will conduct the hotgas from the discharge line 14 into the tank 16. In this connection, it should be noted that the discharge from the line 37 into the tank 16 is effected through a very small orifice indicated at 37a but not actually shown. This causes the hot gas to pass slowly through the pipe lines 14and 37 into'the tank 16 and up through the valve '33 and the line 32 into the suction line 23. This operation is effected to bring the hot gas close to the unit-to be defrosted whereby this hot gas may enter that unit.

It should be noted that'if this system'is connectedwith other evaporators, a pipe 8a is connected in the liquid line 8 and leads to said other evaporators. The line 8a;-is controlled by a valve 3b.

After bringing thehot gas close tothe evaporator 1, the valves 33 and 38 are. closed, the blower 2 is. stopped and the solenoid valvell then closes. Following this closing of the solenoid valve 11, the valve 24 is closed and the valves 18 and 14a are opened WhC16bY I.h6. hot gas will now pass rapidly through the. evaporator 1 for about 30 seconds. At this time, as all outlet valves on the tank 16 are closed, the pressure in the evaporator and tank 16 will equalize. The pressure regulator35 will now open as it is adjusted for example to a pressure of from 10 to 15 lbs. below compressordischarge pressure.

This opening of the pressure regulator will permit the gas to pass through the pipe line 34- and line 32 to suction line 23, whereby the compressor will continue its operation to produce hot refrigerant.

The pressure,regu1ator35-imay be adjustedas. desired to control the rate of flow of hot gas to the evaporator 1, best to obtain the desired defrosting results.

The compressor 3 is maintained in operation during the defrosting operation of the one unit here shown. After the evaporator is defrosted, this usually requiring from 3 to minutes depending upon capacity of the system, the valves 14a and 18 are closed, valves 13 and 11 are opened and the blower 2 is now started.

The liquid level in the tank 16 when the defrosting operation is completed, will rise to a level causing the float unit 25 to actuate the switch 27 so that the solenoid valve 28 will close. The check valve 40 will open under pressure from the tank-16, the. valve 41 being normally open, and the liquid refrigerant in the tank will now flow through the pipe line 39 into the line 8 and thence into the evaporator, without passing through the liquid receiver 7.

When the liquid is boiled out of the tank 16 and the level is lowered a predetermined extent, the float unit 25 will actuate the switch 27 whereby the solenoid 28 will open and the system will now operate on the normal refrigerating cycle, the pressure in the line 8 operating in the line 39 to close the check valve 40.

Although I have herein shown and described only one form of refrigerating system including one form of defrosting means therefor, it is to be understood that various changes and modifications may be made therein without departing from the spirit of the invention and the spirit and scope of the appended claims.

What I claim is:

1. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and control means connected normally in refrigerant flow relationship; defrosting means including a tank; means for conducting hot refrigerant from the compressor through the evaporator; a drain pipe line leading from said evaporator to said tank; and means operable responsive to the liquid level in said tank for returning refrigerant from said tank to said evaporator without passing through said liquid receiver upon completion of a defrosting operation.

2. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and control means connected normally in refrigerant flow relationship; defrosting means including a tank; means for passing hot refrigerant into the evaporator from the outlet side of the evaporator; means for draining liquid from the inlet side of the evaporator into said tank; and means operable responsive to the level of the liquid in said tank and the operation of said compressor for returning liquid refrigerant to said evaporator independently of said liquid receiver upon completion of a defrosting operation.

3. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and control means connected normally in refrigerant flow relationship; defrosting means including a tank; means for circulating hot refrigerant through said evaporator; means for draining from said evaporator into said tank the liquid refrigerant which condenses in the evaporator during defrosting; means for returning the liquid from said tank into said evaporator upon completion of a defrosting operation; and float operated means responsive to the liquid level in said tank for controlling the flow of liquid from said tank to said evaporator.

4. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and flow control means connected normally in refrigerant fiow relationship; defrosting means including a tank; means for circulating hot refrigerant through said evaporator; means for draining from said evaporator into said tank the liquid refrigerant which condenses in the evaporator during defrosting; means for returning the liquid from said tank into said evaporator upon completion of a defrosting operation, and float operated means responsive to the liquid level in said tank for controlling the flow of liquid from said tank to said evaporator and restoring the system to normal refrigerant flow relationship.

5. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and control means connected normally in refrigerant flow relationship; defrosting means including a tank; means for conducting hot refrigerant into outlet side of the evaporator; means for draining from the intake side of the evaporator into said tank the condensation resulting from passing the hot refrigerant into said evaporator; means responsive to the operation of the compressor and the pressure in said tank for returning liquid from said tank to the evaporator; and a float actuated means responsive to the level of the liquid in said tank for restoring the system to normal refrigerant flow relationship following the defrosting operation.

6. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and flow control means connected normally in refrigerant flow relationship; defrosting means including a tank; means for conducting hot refrigerant from the compressor through the evaporator; a drain pipe line leading from said evaporator to said tank; and means for returning refrigerant from said tank to said evaporator without passing through said liquid receiver upon completion of a defrosting operation; means connecting said tank to the suction side of said compressor, valve means for controlling said connecting means; and float actuated means responsive to the liquid level in said tank for restoring the system to normal refrigerant flow relationship.

7. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and flow control means connected normally in refrigerant flow relationship; defrosting means including a tank; means for conducting hot refrigerant from the compressor through the evaporator; a drain pipe line leading from said evaporator to said tank; and means for returning refrigerant from said tank to said evaporator without passing through said liquid receiver upon completion of a defrosting operation, means connecting said tank to the suction side of said compressor, a pressure regulator-operated valve means in said connecting means; means for conducting hot refrigerant to said tank thence through said pressureregulator-operated valve means and said connecting means to said compressor; and means responsive to the liquid level in said tank for restoring the system to normal refrigerant flow relationship.

8. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and flow control means connected normally in refrigerant flow relationship; defrosting means including a tank; means connected in the system for shutting off flow of refrigerant from said receiver; means for circulating hot refrigerant through said tank and said evaporator; means for conducting liquid from said evaporator into said tank during the defrosting operation; means connected in the system for conducting liquid from the tank back into the evaporator upon completion of a defrosting operation, responsive to operation of said compressor and independently of said liquid receiver; and float actuated means responsive to the liquid level in said tank for restoring the system to normal refrigerant flow relationship.

9. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and flow control means connected normally in refrigerant flow relationship; defrosting means including a tank; means connected in the system for shutting off flow of refrigerant from said receiver; means for circulating hot refrigerant through said tank and back to the compressor to maintain the compressor in operation for producing hot refrigerant; said last-named means including a pressure regulator-operated valve responsive to pressure in said tank; means for circulating hot refrigerant through said evaporator; means for conducting liquid from the evaporator to said tank; means for returning liquid refrigerant from said tank to said evaporator without passing the liquid through said liquid receiver upon completion of a defrosting operation; and means responsive to the liquid level in the tank for restoring the system to normal refrigerant flow relationship following said return of said liquid to said evaporator.

10. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and control means connected normally in refrigerant flow relationship; defrosting means including a tank, means for passing hot refrigerant into the evaporator; means for draining liquid from the evaporator into said tank; and means for conducting liquid from said tank to said evaporator independently of said liquid receiver, said means operable responsive to a predetermined level of liquid in said tank and the operation of said compressor.

11. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and control means connected normally in refrigerant flow relationship; defrosting means including a tank; means for conducting hot refrigerant into outlet side of the evaporator; means for draining from the intake side of the evaporator into said tank the condensation resulting from passing the hot refrigerant into said evaporator; means responsive to the operation of the compressor and the pressure in said tank for returning liquid from said tank to the evaporator; a float actuated means responsive to the level of the liquid in said tank for restoring the system to normal refrigerant flow relationship following the defrosting operation; an oil sump connected with said tank; and means connecting said sump with said system including an oil separator and a flow line leading to the suction side of said compressor through said separator.

12. In a refrigerating system including a compressor, a condenser, a liquid receiver, an evaporator and flow control means connected normally in refrigerant flow relationship; defrosting means including a tank; means for conducting hot refrigerant from the compressor through the evaporator; a drain pipe line leading from said evaporator to said tank; and means for returning refrigerant from said tank to said evaporator without passing through said liquid receiver upon completion of a defrosting operation, means connecting said tank to the suction side of said compressor, a pressure regulator-operated valve means in said connecting means; means for conducting hot refrigerant to said tank thence through said pressure-regulator-operated valve means and said connecting means to said compressor; means responsive to the liquid level in said tank for restoring the system to normal refrigerant flow relationship; an oil sump connected with said tank; said system having an oil separator; and a flow line connecting said sump with said compressor through said separator.

References Cited in the file of this patent UNITED STATES PATENTS 2,444,514 Kubaugh July 6, 1948 2,618,129 Williams Nov. 18, 1952 2,643,524 Wilbushewich June 30, 1953 

